serves as a code for the structure of the proteins produced within the cell;
a gene is sequence of DNA nucleotides that codes for a specific protein(s).

RNA structure, function and types:

Structure..

it is a single stran of nucleotides, with the base uracil instead of thymine and with the sugar ribose

RNA structure, function and types:

3 types.. and explain each..

1. messenger RNA (mRNA) copies the DNA stran and carries it to the cytoplasm to a ribosome.
2. transfer RNA (tRNA) delivers the correct amino acid to the ribosome.
3. ribosomal RNA (rRNA) is a component of the ribosome.

genetic code

is the system in which four nucleotides (nitrogenous bases) code for the amino acid sequences of all proteins.

transcription

is the process whereby mRNA makes a copy of the DNA with the aid of RNA polymerase (an enzyme)

translation

is the process whereby the message in the mRNA is translated into the sequence of amino acids that will comprise a protein

DNA replication

is a semi-conservative process in which a copy of the DNA molecule is produced (DNA to DNA)

mutations are

any changes that occur in the DNA structure; mutations can have no effect or serious effects

cell cycle (interphase)

period of activity before a cell undergoes mitosis

types of cell division

mitosis and meiosis

mitosis

occurs in somatic cells (all cells of body except sex cells)

produces new cell (daughter) that have the same number of chromosomes as the original cell (parent0

prophase

chromatin condenses into chromosomes that are duplicated DNA (sister chromatids) held together at the centromere; nuclear envelope disappears

nuclear membranes form around each set of chromosomesp; and cytokinesis occurs (a cleavage furrow forms between the two nucleuses)
*two cells with the same number of chromosomes are produced form one cell

meiosis

occurs in sex cells and reduces the chromosome number by 1/2

phases of meiosis II

are identical to the phases of mitosis; results in 4 cells with 1/2 chromosome number